This document discusses lung cancer, including its risk factors, presentation, diagnosis, staging, prognosis, and different types. It notes that cigarette smoking is the leading risk factor, accounting for 85% of lung cancers. Radon exposure and asbestos are also significant risk factors. The main types of lung cancer are small cell carcinoma and non-small cell carcinoma (which includes adenocarcinoma, squamous cell carcinoma, and large cell carcinoma). Diagnosis requires biopsy and imaging can reveal solitary pulmonary nodules. Prognosis is generally poor due to lack of effective screening.